The purpose of this study is to extend prior research on the effects of endotracheal suctioning (ETS) in head-injured adults by comparing two hyperoxygenation protocols. The protocols will be administered between ETS passes as a means of controlling increases in intracranial pressure and preventing compromised cerebral perfusion pressure. Specific aims of this study are: 1) to compare the effects of two hyperoxygenation protocols: [hyperventilation/-hyperinflation (HV/HI) protocol versus four breath hyperinflation (HI) protocol] administered between two ETS passes on mean arterial pressure (MAP), mean intracranial pressure (MICP), cerebral perfusion pressure (CPP), heart rate (HR), oxygen saturation (SaO2), end- tidal CO2, (PETco2), and secretion recovery in adult head-injured patients; and 2) to determine the difference in these two hyperoxygenation protocols in open versus closed head-injured patients; and 2) to determine the difference in these two hyperoxygenation protocols in open versus closed head-injured patients. This is a quasi-experimental, within subject, between group repeated measure design. The independent variables is the hyperoxygenation protocol (HV/HI versus HI protocol). The dependent variables are the physiological measurements of MAP, MICP, CPP (calculated value), HR, SaO2, PETco2 and secretion recovery. The suction variables to be controlled are F10s, suction flow rate and suction duration. Six physiological parameters (MAP, MICP, CPP (calculated), HR, SaO2, PETco2) will be recorded simultaneously prior to, during and following the endotracheal suctioning sequence by means of a Gould TA2000 recorder. All pressure transducers (MAP & MICP) will be calibrated against a column of mercury; PETco2 and SaO2 will be validated by arterial blood gases at pre and post protocol; HR will be validated by the subject's EKG monitor; secretion recovery will be measured by means of a PM 460 Precision Electronic Mettler Balance to the nearest thousandth gram. Data analysis of Specific Aim 1 will consist of a two way within-subject, repeated measure analysis of variance to determine the effects of the HV/HI versus HI protocol on the dependent variables. For specific Aim 2 data analysis will consist of a within-subject, between-group, repeated measures analysis of variance to determine the effects of HI protocol on open versus closed head injured adults on the dependent variables and a within-subject, between group repeated measures ANOVA to determine the effects of HV/HI protocol on open versus closed head injured adults on the dependent variables.